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To all whom it may concern:

Be it known that 1, CHARLES P. HIDDEN, a citizen of the United States, residing at Providence, in the county of Providence and State of Rhode Island, have invented certain it new and useful Improvements in Methods of Hydrolyzing qCyanid to Ammonia, of which the following is a specification.

This invention relates to the production of ammonia from sodium cyanid or the like, and more especially concerns an improvement upon the process disclosed in the patcut to John E. Bucher, No. 1,091,425, dated Mar. 24., 1914.

In said patent there is described a method of fixing tree nitrogen in the form ofalkali metal cyanid, by forming an intimate mixture of, for example, sodium carbonate, finely divided iron and carbonaceous mate rial, and subjecting said mixture to the action of free nitrogen, in a retort heated to a bright red heat, but preferably" not above the eutectic point; of the carburized iron formed.

In practice, the resulting mixture contains the catalytic pulverized iron, which is substantially unchanged, save that it is normally hi hly carburized; the alkali metal cyanid, Formed by the reaction; residual coke or the like; and the residual orunconverted alkali metal carbonate,-together, frequently, with traces of compounds resulting from impurities in the coke, or other source of carbon, used. a

The patent in question describes this production of alkali metal cyanid in detail, and

thereafter sets forth the formation of ammonia through the reaction of steam upon the cyanized material, according to the equationi lit has been found in practice, however,

that certain difficulties are encountered in Specifieation of Letters Patent.

Patented Aug, 5, i919.

Applicatidn and October a, raw. Serial an enema moniasince while the reaction may be empirically expressed as perthe above equation, as a matter of tact, it is very much more complex; ammonium carbonate, sodlum cyanate, iron. oxid, sodium terrocyanid, etc, being formed together with the ammonia. Some of these by-productspsuch as the iron oxid, arefinal, while others are more or less intermediate, and their extent of pro-.

duction depends upon the composition of the reactive mass,'th e temperature or temperatures at which hydrolysis is efiected, the quantity of steam supplied, its condition (dry or wet), its temperature, etc.

The mass containing the alkali metal cyanid to be hydrolyzed is preferably briquet- -ed, and may conveniently be supplied after proper cooling, direct from the cyanizing operation described in the patent to said John E. lBucher, No. 1,120,682, dated Dec. 15, 1914:. In thiscase the cyanized briquets comprise the finely divided catalytic iron (or its equivalent), unconverted alkali metal carbonate, alkali metal cyanid, carbon, at times some sodium cyanate, possibly even some traces of sodium ferrocyanid, and

traces of compounds resulting from the sili- (210115 or alumlnous 1mpur1t1es commonly present in coke or like carbon supplying material which is not ash-free, but which is available for use in the cyanizing operation.

when really aslrtree carbon cannot readily be obtained.

Any alkali metal cyanate initially present" in the briquets to behydrolyzed, or which is formed during the hydrolyzing operation,

normally is converted to ammonia during the course otsuch operation it proper rethe greater part of the hydrolyzing operathan the upper limit of the same.

tion at temperatures nearer the lower limit of the range of permissible temperatures,

Thus I prefer to start the steaming treatment with the cyanized mass at a temperature of about 275 C. and to then allow the temperature to rise, as it of course tends to do, very gradually toward, say, from 600 C.

to 650 C. I also prefer not to materia-lfy exceed the latter temperature.

The steam supplied to the cyanized briquet charge, is most desirably dry. Even then, there is still a tendency for the yield of ammonia to be far from quantitative, if the steam be supplied at or above atmospheric pressure; especially as the temperature of the mass being hydrolyzed begins to rise.

What apparently takes place in such case, is that too rapid hydrolysis is effected in the interior of a mass which is a poor conductor of heat, so that the temperaturerises .in parts of the charge to such an extent that the large amount of water vapor or steam present is-enabled to form considerable alkali metal ferroeyanid and other undesirable products.

To thereafter efliciently decompose this large amount of ferrocyanid, requires time and the effecting of this decomposition at undesirably high temperatures which delesaid partial. vacuum.

The effect of this rarefication of the steambecomes apparent substantially as soon as any material reduction in pressure is established during the hydrolyzing operation; but I prefer to maintain'the pressure in said receptacle at from but one quarter to one'half of that of the atmosphere. By thus employing dry steam under reduced pressure and by suitable temperature regulation to maintain the temperature substantially throughout the reactive mass well below 600 for the major portion of the 0 eration, very nearly quantitative yields 9. 98 or 99% or more) of ammonia, in vaporous form may be obtained.

The so produced ammonia may, of course, be collected in water or in any other manner desired.

Finally, I desire to call attention to the advantage of using for the hydrolyzing operation, a charge which is briqueted rather than loosely pulverulent in character. The briquets of the type in question are exceedingly porous and particularly well adapted for hydrolysis; since no binding materials such as tar or thelike, or even the heat treated residues ofsuch material, are present in the pores of said bri uets, to obstruct the free access of the rarehed water vapor to the cyanid content of said briquets.

Being thus porous, also, the briquets do not tend to locally overheat, as much as does a pulverulent mass, since the vapors can circulate more freely and thereby tend to distribute the heat evolved more equally.

Having thus described my invention, what I claim is:

1. The method of forming ammonia which comprises treatin a briqueted charge of intimately mixed al (ali metal cyanid, iron, carbon and an alkali metal oxygen compound, with dry steam, under a pressure below that of the atmosphere, to hydrolyze said cyanid to form ammonia and an additional amount of said alkali metal oxygen compound.

2. The method of forming ammonia which comprises treating a porous briqueted cyanized charge with dry steam, under a pressure substantially below that of the atmosphere, to hydrolyze to ammonia the cy anogen compound )resent in said charge.

3. The method of forming ammonia which comprises hydrolyzing a cyanized charge with dry steam, under a pressure substantially below that of the atmosphere, while maintaining the temperature of the hydrolyzing operation below 650 C. during sub- 'stantially the whole of said operation.

I. The method of forming ammonia which comprises hydrolyzing a cyanogen compound with dry steam, under a pressure below that of the atmosphere, while maintaining the temperature of the hydrolyzing op- I eration between 275 C. and 650 C. during substantially the whole of said operation.

In testimony whereof I have afiixed my signature, in the presence of two witnesses.

CHARLES P. HIDDEN.

Witnesses:

ROGER N. LoBDELL, 

